Electric-telephone system.



No. 684,303. Patented Oct. 8, l90l.

W. E. PEMBLETON. v

ELECTRIC TELEPHONE SYSTEM.

(Application filed Jan. 18, 1901.)

(No Model.)

UNITED STATES PATENT OFFICE.

lVILLIAlVI E. PEMBLETON, OF WITTENBERG, VISOONSIN.

ELECTRIC-TELEPHONE SYSTEM.

SPECIFICATION formingpart of Letters Patent No. 684,303, dated October8, 1901.

Application filed January 18, 1901. Serial No. 43,714. (No model.)

To all whom it ntcty concern.-

Be it known that I, WILLIAM E. PEMBLETON, a citizen of the UnitedStates, and a resident of VVittenberg, in the county of Shawano andState of Wisconsin, have invented certain new and useful Improvements inElectric-Telephone Systems; and I do hereby declare that the followingis a full, clear, and exact description thereof.

My invention has for its object to eliminate resistance of the coils ofcall-signal magnetos from talkin g-circuits of electric-telephonesystems; and it consists in what is hereinafter particularly set forthwith reference to the accompanying drawing and subsequently claimed.

The drawing is a diagram illustrating an application of my invention.

Referring by letter to the drawing, A B indicate a pair of parallelconductors constituting the line of an electric-telephone system towhich my invention is applicable. Between the conductors all thetelephones on the line are bridged in the usual manner, normally in opencircuit. At a central station on the line the secondary of aninduction-coil C is bridged between the conductors aforesaid by anelectric resonator D, and in normally open circuit with the primary ofsaid coil are a magneto E, a spring contact-plate b, and an adjustablecontact point 0, these contacts serving as means for making and breakingthe circuit. The resonator is shown as comprising a pair ofconductor-plates, an intermediate insulating-plate, and opposingconductor screws, these screws being adjustable in all the plates tovary the spark-gap, this gap being shown in the sectional illustrationof resonator D constituting part of central-station equipment. At theaforesaid station the secondary of another induction-coil F connectsconductor B and ground through an electric resonator G, that ispreferably similar in detail to the one above specified, an electriccall-bell or other electric signaling device being electricallyconnected to both terminals of the primary of said coil.

At each of the substations on the line is an induction-coil I, havingthe secondary thereof in circuit with an electric resonator J andconductors A B, this resonator being preferably similar in detail tothose set forth in the foregoing. A switch K is employed to at times outout conductor A and put a terminal wire L, connected to ground, inclosed circuit with the secondary of coilI, the resonator J, andconductor B. The primary of induction-coil I is in circuit with amagneto M and an electric call-bell N or other electric signalingdevice, this circuit being normally closed by a switch-blade P in touchwith a contact-point d, as herein shown. Springcontacts efare shownarranged in opposite directions from switch-blade P, normally out oftouch with same and electrically connected to be in acircuit withmagneto M and primary of induction-coil I.

To signal from central station to a substation, contact of plate I) ishad with point 0 and magneto E operated to generate current ofsufficient strength in the then closed circuit that includesinduction-coil O, resonator D, conductor A, induction-coil I,resonatorJ, and conductor B, whereby the signal N is energized, it beingunderstood that switch K is then in normal position to complete metalliccircuit. To signal central station from a substation, switch K is swungto touch on the adjacent terminal of ground-wire L, and contact f ismoved againstswitch P to force the latter out of touch with contact atand into touch with contact e,.after which the magneto M is operated togenerate a current of sufficient strength through induction-coil I,resonator J, conductor B, resonator G, and inductioncoil F, whereby theelectric signal H is energized.

By employment of an electric resonator to obtain a spark-gap orair-space in circuit with an induction-coil, as herein shown anddescribed, it is evident, as an electrical law, that current of lowpotential, regardless of amperage,pwill not pass a spark-gap between oneconductor and another; but if the current be of sufiiciently highpotential, no matter how low the amperage, it will readily cross saidgap, and thereafter the resistance of same is not materiallyappreciable. Hence it will be understood that the ordinary lowpotentialvoice-current used in telephony will not cross the spark-gap of aresonator such as is herein shown and described. Consequently theresonator is effective as a barrier for voice currents withoutmaterially increasing the resistance of the signal-circuit in which itis placed, the induction-coil in' this same circuit being utilized totransform the current of an ordinary magneto-electric generator into acurrent of high potential, but of corresponding low amperage.

From the foregoing it will be readily understood that the ordinarylow-voltage currents for talking-circuits on the line will follow theconductorsA B and that currents of higher Voltage are requisite forenergizing the signal devices, the latter currents passing from one tothe other of said conductors across the spark-gaps of the electricresonators arranged as herein set forth.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is-

1. An electric-telephone system having the call-signal devices thereofin circuit with induction-coils, electric resonators and talkingcircui tconductors, together with means for generating current sufficient tocross the spark-gaps of resonators in a closed callingcircuit.

2. An electric-telephone system having the call-signal devices thereofin circuit with induction-coils, electric resonators, talking-circuitconductors and sources of current, togetherwith means for closingcalling-circuits, the current from any of the sources aforesaid beingsufficient to cross the resonators in the calling-circuit therewith.

3. An electric-telephone system having central station thereof providedwith a source of current in normally open circuit with aninduction-coil, an electric resonator and talking circuit conductors, anelectric signal device at said station in circuit with an inductioncoil,an electric resonator, one of said conductors and ground, a magneto ateach substation in normally open circuit with an induction-coil,electric resonator and aforesaid conductors, an electric signal deviceat each substation in normally closed metallic circuit with the induction-coil and resonator thereat,

as Well as with said conductors, means for switching current frommetallic circuit to ground, and other means for putting the WILLIAM E.PEMBLETON.

Witnesses:

WM. G. HEINS, OLIVE ANDERSEN.

